Oxford scientists discover elephant 'bee warning' call

Elephants have a specific call to warn the herd of the presence of angry bees.

A team of scientists from Oxford University, Save the Elephants, and Disney’s Animal Kingdom studied elephant families, including individuals that the team already knew, in the Samburu and Buffalo Springs National Reserves in Kenya.

Scientists know from previous studies that the elephants will make a specific noise to mark the impending arrival of a calf as well as warn of the presence of humans but wanted to test whether any other perceived dangers would have a call. The team also knew that elephants will flee when a bee colony is accidentally disturbed, but set about recording the elephants' actual reactions. "In our experiments we played the sound of angry bees to elephant families and studied their reaction," explains Lucy King who led the research. "Importantly we discovered elephants not only flee from the buzzing sound but make a unique 'rumbling' call as well as shaking their heads."

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The experiment comprised 15 bee sound and 13 white noise playback trials. The sounds came from a camouflaged speaker, which was between 8 and 18m from the nearest subject. The experiment took place in the dry season of February to March 2008. To record the elephants' response, the team used three audio-recording units -- two in a duffle bag near to the herd and another on the roof of the research vehicle.

Acoustic features measured included call duration, mean and range of the fundamental frequency, and the mean and range of call amplitude.

The scientists report in a paper published by the journal PLoS One noted that the most obvious effect of the bee recording was that the elephants would flee: "In 14 out of 15 bee trials (93 percent), families had moved away, compared to six of 13 white noise control trials (46 percent)", they state. The elephants also shook their heads and threw dust around, which the team suggested "would knock bees away&hellip;lower[ing] the risk of being stung."

However, the recording equipment also picked up a specific call that the elephants made. The team isolated the specific acoustic qualities associated with this rumbling call and played the sounds back to the elephants to confirm that the recorded call triggered the elephants’ decision to flee even when there was no buzzing and no sign of any bees. "We tested this hypothesis using both an original recording of the call, a recording identical to this but with the frequency shifted so it resembled a typical response to white noise, and another elephant rumble as a control," said King. "The results were dramatic: six out of 10 elephant families fled from the loud speaker when we played the ‘bee rumble’ compared to just two when we played a control rumble and one with the frequency-shifted call (caught on film). Moreover, we also found that the elephants moved away much further when they heard the 'bee' alarm call than the other rumbles."

The team is now going to investigate whether this specific call is used to warn of other dangers as well, but say that the initial findings suggest elephants have something comparable to a language. "The calls give tantalising clues that elephants may produce different sounds in the same way that humans produce different vowels, by altering the position of their tongues and lips," said Dr Joseph Soltis of Disney’s Animal Kingdom. "It’s even possible that, rather like with human language, this enables them to give superficially similar-sounding calls very different meanings."